Exploiting Nonlinearity to Design Robust Wireless Power Transfer and Wideband RF Energy Harvesting

In this paper, the design of position-insensitive wireless power transfer (WPT) circuits and wideband RF wireless energy harvesting (WEH) circuits are presented. The unique properties of a specific class of nonlinear resonant circuits described by a 2 nd order nonlinear differential equation with cubic or higher order nonlinear terms are exploited to design such circuits.The position-insensitive WPT circuit maintains a high power transmission efficiency (PTE) over large transmission distance and misalignment variations without tuning the source’s operating frequency or employing tunable matching networks and active feedback/control circuitry. The wideband WEH circuit utilizes a nonlinear resonant circuit to significantly enhance its bandwidth. Both a WPT and a WEH circuit have been designed and tested. The WPT circuit achieves a constant power transfer and PTE of 20 W and 85%, respectively, over a varying transmission distance of 250 mm. On the other hand, the WEH circuit using a nonlinear resonator achieves 2.7 times bandwidth enhancement as compared to a similar circuit employing a linear resonator having the same quality factor,Q.